SBOSAE0B April   2023  – September 2023 PGA855

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Device Comparison Table
  7. 6 Pin Configuration and Functions
  8. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Gain Control
      2. 8.3.2 Input Protection
      3. 8.3.3 Output Common-Mode Pin
      4. 8.3.4 Using the Fully Differential Output Amplifier to Shape Noise
    4. 8.4 Device Functional Modes
  10. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Linear Operating Input Range
    2. 9.2 Typical Applications
      1. 9.2.1 ADS127L11 and ADS127L21, 24-Bit, Delta-Sigma ADC Driver Circuit
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curves
      2. 9.2.2 ADS8900B 20-Bit SAR ADC Driver Circuit
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Development Support
        1. 10.1.1.1 PSpice® for TI
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.1 Overview

The PGA855 is a monolithic, high-voltage, precision programmable-gain instrumentation amplifier. The PGA855 combines a high-speed current-feedback input stage with an internally matched gain resistor network, followed by a four-resistor, fully differential amplifier output stage. Eight preprogrammed binary gains, ranging from 0.125 V/V to 16 V/V are selectable using gain-select pins A0, A1, and A2.

A functional block diagram for PGA855 is shown in the next section. The differential input voltage is fed into a pair of matched, high-impedance input-current-feedback amplifiers. An integrated precision-matched gain resistor network is used to amplify the differential input voltage. A fully differential output difference amplifier, A3, rejects the input common-mode component and refers the output signal to the voltage level set by the VOCM pin.

The PGA855 output amplifier bandwidth is optimized to drive high-performance analog-to-digital converters (ADCs) with sampling rates up to 1 MSPS without the need for an additional ADC driver. The output amplifier uses a separate power supply that is independent of the input-stage power supply. When driving an ADC, use a low-impedance connection from LVDD and LVSS to the ADC power supplies. This configuration protects the ADC inputs from damage due to inadvertent overvoltage conditions.